1. Field of the Invention
This invention relates to a new and useful polymorph, and more particularly it pertains to a novel polymorph, crystalline racemic 9.alpha.,11.alpha.15(S)-trihydroxy-5-cis,13-trans-prostadienoic acid.
2. Description of the Prior Art
Racemic 9.alpha.,11.alpha.,15(S)-trihydroxy-5-cis,13-trans-prostadienoic acid, also known as dl-prostaglandin PGF.sub.2.sub..alpha., is a recently synthesized, colorless, oily racemate, J. Am. Chem. Soc., Vol. 91, pages 5675 to 5677, 1969 and Chem. Comm., No. 6, pages 304 to 305, 1969, that possesses valuable, therapeutic properties. The properties broadly include the ability to modify smooth muscle activity, the termination of pregnancy, induction of labor, and induction of menses. Prostaglandins, Progress in the Chemistry of Fats and Other Lipids, Vol. IX, Part 2, pages 231 to 278, 1968, Pergamon Press, Inc.
While the above mentioned therapeutic properties of the oily racemate are known to the prior art through 9.alpha.,11.alpha.,15(S)-trihydroxy-5-cis,13-trans-prostadienoic acid, [PGF.sub.2.sub..alpha. ], the art apparently never used the oily racemate because it would encounter problems in its attempts to obtain and to use the oily racemate for therapeutic purposes. For example, typical problems that would be encountered by the art include the difficulty to obtain and to keep essentially pure racemic PGF.sub.2.sub..alpha. because the oily racemate would decompose during its distillation and also because it would readily oxidize during storage to presently unidentified products that lack prostaglandin utility. Another problem that would be encountered with the oily racemate would arise in using the oily racemate in conventional pharmaceutical dosage forms and in drug delivery devices. In the pharmaceutical forms, the oily racemate would undergo air oxidation and leakage therefrom. In the drug delivery devices comprising a rate release membrane containing the oily racemate, there would be uncontrolled passage of the oily racemate from the rate release membrane to essentially prevent its administration at a programmed rate over a predetermined time period to produce a therapeutic effect. Thus, in view of the foregoing discussion, it can readily be seen that the art critically needs a novel and useful form of the racemic 9.alpha.,11.alpha.,15(S)-trihydroxy-5-cis,13-trans-prostadienoic acid that possesses improved drug stability and can advantageously be used in pharmaceutical dosage forms or in drug delivery devices for its outstanding therapeutic properties.